Communication System And Communication Method For Providing IP Network Access To Wireless Terminals

ABSTRACT

A communication system for providing an access to an IP network to a wireless terminal, comprising a gateway for passing data from the wireless terminal to the IP network, wherein the gateway comprises a first group of servers with a receiving unit for receiving data from the wireless terminal, a selecting unit for selecting one of a plurality of destination addresses based on a header of the received data, and a forwarding unit for forwarding the data to the destination address selected by the selecting unit, wherein each of the first group of servers forwards the data to a server constituting a second group of servers corresponding to one of the plurality of destination addresses.

TECHNICAL FIELD

The present invention relates to a communication system and acommunication method for providing access to an IP network to a wirelessterminal.

BACKGROUND ART

In recent years, retail sales of wireless communication lines have beengrowing with the emergence of mobile virtual network operators (MVNOs).Conventionally, mobile network operators (MNOs) having a wirelesscommunication infrastructure have directly provided wirelesscommunication services to end users. An MVNO provides a unique wirelesscommunication service to an end user, using the wireless communicationinfrastructure of an MNO.

The MVNOs can be roughly classified into a form in which the MVNO doesnot have any communication infrastructure at its own company, and a formin which the MVNO has its own communication infrastructure and connectsthe communication infrastructure to the communication infrastructure ofan MNO to provide a wireless communication service (see FIG. 1). Incomparison with the former case, the latter case has the communicationinfrastructure in its own company, and thus can set the price accordingto the communication quality such as communication speed, communicationcapacity, and the like, and attempts to meet various needs. For example,SIM cards for wireless communication services, prices for which aresuppressed by setting the maximum communication capacity that enableshigh-speed data communication, are sold at mass retailers.

To be specific, such an MVNO receives a SIM card from an MNO and furtherprovides the SIM card to the end user. The MVNO manages thecommunication quality such as the speed limit and the capacity limit setfor each SIM card together with an identification number of each SIMcard in a database, and provides a wireless communication serviceaccording to contract content of a mobile terminal such as a smartphoneor a tablet that has requested an access to the Internet.

In some cases, a mobile virtual network enabler (MVNE) that provides asupport service for the MVNO to carry out smooth business intervenesbetween the MNO and the MVNO, and the MVNE may receive a SIM card fromthe MNO and further provides the SIM card to the MVNO.

In a case where the MVNO or the MVNE holds a gateway (GGSN in 3G or P-GWin LTE) that is an end point of a core network, as its own communicationinfrastructure, L2 connection (full MVNO connection (an S5/S8 interfacein LTE or a Gn interface in 3G)) becomes available with thecommunication infrastructure (3G SGSN or LTE S-GW) of the MNO, and an L2tunnel is formed between a wireless terminal equipped with the enduser's SIM card and the gateway. The L2 connection has attractedattention because it provides a higher degree of freedom of designingwireless communication services than L3 connection (light MVNOconnection).

SUMMARY OF INVENTION Technical Problem

The gateway that needs to be held by the MVNO or the MVNE for the L2connection is expensive hardware that costs hundreds of millions of yenper unit, and the number of simultaneously connectable devices is valuedas its performance. If additional data processing is performed in thegateway to meet various needs, the processing inevitably leads toreduction in the number of simultaneously connectable devices due to aphysical limitation of a server on which the gateway is implemented.

The number of gateways connectable with the communication infrastructureof the MNO by the MVNO or the MVNE is determined in advance by the MNO.Mostly, a limit is put on the number of devices. Even if the cost isignored, an increase in the number of simultaneously connectable devicesby adding a larger number of hardware than the number limit is notacceptable.

For example, what has been remarkably increasing in recent years as theneed for wireless communication services is the movement of IoT to add awireless communication function to everything to enable them to beconnected with the Internet. Hereinafter, a wireless device connectableto a computer network including the Internet is referred to as “IoTdevice”. Examples of the IoT device include mobile terminals such assmart phones and tablets held by humans, and are also spreading intodevices that require communication in a different form from humans, suchas moving means such as automobiles, which move faster than humans, andsensors that do not move from a specific position. With the spread, therequired communication speed and the required frequency of communicationare diversified. In a case of incorporating an SIM card into anindustrial machine to make the industrial machine be an IoT device, andcausing the industrial machine to remotely communicate with anotherdevice, even if the IoT devices only perform low-capacity communicationat a low frequency, a large number of simultaneous connection isrequired in consideration of the fact that countless devices performcommunication. To meet such needs, a high-value added wirelesscommunication service without suppressing an increase in the number ofsimultaneously connectable devices needs to be realized.

Similar problems may occur in a gateway L3-connected with a wirelessterminal of an end user. Also, as for the gateway held by the MNO,similar problems may occur.

Furthermore, even if additional data processing is not performed in thegateway, the number of simultaneously connectable devices is limited bytunneling processing of a GTP header, and such a load of the dataprocessing impedes realization of an increase in the number ofsimultaneously connectable devices.

The present invention has been made in view of such a problem, and anobject of the present invention is to enable an increase in the numberof simultaneously connectable devices as compared with conventionalcases in a communication system and a communication method for providingan access to an IP network to a wireless terminal.

Solution to Problem

To achieve such an object, a first aspect of the present invention is acommunication system for providing an access to an IP network to awireless terminal, including a gateway for passing data from thewireless terminal to the IP network, wherein the gateway includes afirst group of servers with a receiving unit for receiving data from thewireless terminal, a selecting unit for selecting one of a plurality ofdestination addresses based on a header of the received data, and aforwarding unit for forwarding the data to the destination addressselected by the selecting unit, wherein each of the first group ofservers forwards the data to a server constituting a second group ofservers corresponding to one of the plurality of destination addresses.

Further, according to a second aspect of the present invention, in thefirst aspect, the gateway is GGSN or P-GW.

Further, according to a third aspect of the present invention, in thefirst or second aspect, the communication system further includes agroup of C plane servers receiving a connection initiation request fromthe wireless terminal, wherein the processing of the first or secondaspect performed by the first group of servers is triggered by theconnection initiation request received by the group of C plane servers.

Further, according to a fourth aspect of the present invention, in anyone of the first to third aspects, the number of servers constitutingthe first group of servers is equal to or less than a predeterminednumber.

Further, according to a fifth aspect of the present invention, in thefourth aspect, the predetermined number is determined by an MNO.

Further, in a sixth aspect of the present invention, in any one of thefirst to fifth aspects, the number of servers constituting the secondgroup of servers exceeds the number of servers constituting the firstgroup of servers.

Further, according to a seventh aspect of the present invention, in anyone of the first to sixth aspects, the first group of servers and thesecond group of servers respectively have a correspondence table betweena destination address that was designated by the header and theplurality of destination addresses for each tunnel established by thewireless terminal.

Further, according to an eighth aspect of the present invention, in theseventh aspect, the correspondence table is associated with anidentifier of a GTP header within the header.

Further, according to a ninth aspect of the present invention, in anyone of the first to eighth aspects, the selecting unit specifies one ofa plurality of destination addresses to which the data is forwarded byrewriting a destination address designated by the header.

Further, according to a tenth aspect of the present invention, in anyone of the first to ninth aspects, the plurality of destinationaddresses is determined so as not to allocate the same address.

Further, according to an eleventh aspect of the present invention, inany one of the first to ninth aspects, at least part of the plurality ofdestination addresses are the same.

Further, according to a twelfth aspect of the present invention, in anyone of the first to eleventh aspects, an L2 tunnel is formed as acommunication channel between the wireless terminal and the first groupof servers.

Further, according to a thirteenth aspect of the present invention, inany one of the first to twelfth aspects, each server constituting thesecond group of servers is an instance on a cloud.

Further, according to a fourteenth aspect of the present invention, inthe thirteenth aspect, each server constituting the first group ofservers is an instance on a cloud.

Further, according to a fifteenth aspect of the present invention, inthe fourteenth aspect, the second group of servers is shared by eachserver of the first group of servers.

Further, according to a sixteenth aspect of the present invention, inany one of the thirteenth to fifteenth aspects, a third group of serversconnected to the second group of servers is included, and the thirdgroup of servers controls the number of servers constituting the secondgroup of servers.

Further, according to a seventeenth aspect of the present invention, inthe sixteenth aspect, the third group of servers is constituted byinstances constituting the second group of servers.

Further, according to an eighteenth aspect of the present invention, inany one of the thirteenth to seventeenth aspects, the number ofinstances constituting the second group of servers is reducible to zerodepending on a processing load of the second group of servers.

Further, according to a nineteenth aspect of the present invention, inany one of the thirteenth to eighteenth aspects, the gateway ismulti-tenant.

Further, according to a twentieth aspect of the present invention, inany one of the first to nineteenth aspects, the second group of serversperforms data processing to the data.

Further, according to a twenty-first aspect of the present invention, inthe twentieth aspect, the data processing is at least one of encryptionof payload of the data, protocol conversion of the data, throughputcontrol of data transmission from the wireless terminal and credentialaddition to payload of the data.

Further, according to a twenty-second aspect of the present invention,in any one of the first to twenty-first aspects, the second group ofservers perform downstream data processing to data transmitted from thegateway to the wireless terminal.

Further, according to a twenty-third aspect of the present invention, inthe twenty-second aspect, the downstream data processing is at least oneof resolution conversion of an image or a video included in the data,throughput control of data reception by the wireless terminal, prioritycontrol of data reception by the wireless terminal and execution of afunction compliant with HTML5.

Further, a twenty-fourth aspect of the present invention is acommunication method for providing an access to an IP network to awireless terminal, including steps of: a first group of servers of agateway for passing data from the wireless terminal to the IP networkreceiving data from the wireless terminal at the gateway, the firstgroup of servers selecting one of a plurality of destination addressesbased on a header of the received data, and the first group of serversforwarding the data to the selected destination address, wherein each ofthe first group of servers forwards the data to a server constituting asecond group of servers corresponding to one of the plurality ofdestination addresses.

Further, according to a twenty-fifth aspect of the present invention isa program for having a gateway for passing data from a wireless terminalto an IP network to perform a communication method for providing anaccess to the IP network to the wireless terminal, the communicationmethod including steps of: a first group of servers of the gatewayreceiving data from the wireless terminal at the gateway, the firstgroup of servers selecting one of a plurality of destination addressesbased on a header of the received data, and the first group of serversforwarding the data to the selected destination address, wherein each ofthe first group of servers forwards the data to a server constituting asecond group of servers corresponding to one of the plurality ofdestination addresses.

Advantageous Effect of Invention

According to an aspect of the present invention, in a gateway forpassing data from a wireless terminal to an IP network, a first group ofservers, which receives the data from the wireless terminal, and asecond group of servers, which performs additional data processing ordata processing not performed in the first group of servers, areisolated, whereby data processing using a larger amount of computingresources can be performed in the second group of servers while an upperlimit of the number of simultaneously connectable devices of the firstgroup of servers is increased.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically illustrating an MVNO that connects itsown communication infrastructure to a communication infrastructure of anMNO to provide a wireless communication service.

FIG. 2 is a diagram illustrating an outline of a communication systemincluding a gateway according to an embodiment of the present invention.

FIG. 3 is a diagram exemplarily illustrating a packet transmitted from awireless terminal to a gateway.

FIG. 4 is a diagram illustrating rewriting of a GTP header in anembodiment of the present invention.

FIG. 5 is a diagram illustrating an outline of a communication systemincluding a gateway according to another embodiment of the presentinvention.

FIG. 6 is a diagram illustrating an example of a determination processof correspondence between a first group of servers and a second group ofservers.

FIG. 7 is a diagram illustrating an example of correspondence between afirst group of servers and a second group of servers.

FIG. 8 is a diagram illustrating additional data processing for apayload according to an embodiment of the present invention.

FIG. 9 is a diagram illustrating a flow of data processing of protocolconversion in an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

In the present specification, a case in which an MVNO holds a gatewaywill be described as an example. However, it is noted that the presentinvention is also applicable to a case in which an MVNE or an MNO holdsthe gateway.

The terms MNO, MVNE, and MVNO may be different in their definitiondepending on the country. Hereinafter, description will be given usingan example, in which, as in Japan, an MNO holds 3G SGSN and LTE S-GW ascommunication infrastructures, and an MVNO holds 3G GGSN and LTE P-GW ascommunication infrastructures. In any case, applicability of the presentinvention is unchanged, which enables an increase in the number ofsimultaneously connectable devices even under gateways havingrestrictions on the number of installable devices.

(Outline of Present Invention)

FIG. 2 illustrates an outline of a communication system including agateway according to the present invention.

A communication system 200 according to the present invention is acommunication system for providing an access to an IP network or thelike to a wireless terminal, and includes a gateway 210 for passing datafrom the wireless terminal to the IP network.

The gateway 210 includes a first group of servers 211. For example, thenumber of servers connectable with the MNO's communicationinfrastructure (core network) is limited, which is typically defined bythe MNO and cannot be exceed. For example, IP addresses of the serversconstituting the first group of servers 211 are registered in advance ina database of the MNO, and the MNO determines to which of the servers ofthe first group of servers 211 the data from the wireless terminal istransmitted by reference to a list of the registered IP addresses. Forexample, allocation is made according to the round robin method. Theregistered information may include a destination address for identifyinga destination such as a MAC address, in addition to the IP addresses.

Each of the servers constituting the first group of servers 211 includesa receiving unit that receives data from the wireless terminal, aselecting unit that selects any one of a plurality of destinationaddresses on the basis of a header of the received data, and aforwarding unit that forwards the received data to the destinationaddress selected by the selecting unit.

In an embodiment of the present invention, the forwarding unit rewritesthe IP address designated by the header of the data received from thewireless terminal with one of the plurality of IP addresses. Asillustrated in FIG. 3, the data includes a payload and a header. In FIG.3, a part higher than an HTTP layer is illustrated as the payload.However, focusing on a GTP header, a part higher than the GTP layer(left side in FIG. 3) can be seen as the payload, in this case, a GTPpayload.

As illustrated in FIG. 4, rewriting can be performed by rewriting the IPaddress designated by an IP header in the header. To be specific, thefirst group of servers 211 determines an identification number of a SIMcard such as IMSI or ICCID from an identifier (TEID) in the GTP headerincluded in an IP packet that has arrived, to identify which wirelessterminal the data is from, and can rewrite the IP address with an IPaddress of one of servers of a second group of servers 212 associatedwith the identifier.

Further, rewriting is an example of processing necessary for forwardingdata received by each server of the first group of servers 211 to aserver configuring the second group of servers 212, and other tunneling(IPIP, GRE, IPsec, GTP, or the like) can be performed to transfer thedata.

The selecting unit can determine the plurality of IP addressescorresponding to the second group of servers 212 at the destination,from a private IP address or global IP address space such that the sameIP address is not allocated to the plurality of servers of the secondgroup of servers 212 at the same time. Further, the selecting unit canallocate at least parts of the plurality of IP addresses to theplurality of servers at the same time as the same IP address. In thiscase, one of the servers to which the same IP address has been allocatedis made active and the other servers are set to stand by. Further, apart of the IP addresses can be made accessible only for a specificidentifier (TEID) according to contract content. Further, each of thefirst group of servers 211 and the second group of servers 212 can holda correspondence table between the IP address before rewriting, whichhas been designated by the header, and the plurality of IP addressesafter rewriting, for each L2 or L3 tunnel. Each correspondence table canbe associated with each wireless terminal by the identifier in the GTPheader or the like. Further, only the second group of servers 212 mayhave the correspondence table, and the first group of servers 211 mayinquire of the second group of servers 212.

Here, as an operation of the gateway 210, the description is made mainlyassuming a case in which communication is performed on a U plane of GTPfor an access to the IP network after an L2 tunnel is formed as acommunication channel between the gateway 210 and a mobile terminal.However, rewriting of the IP address can be similarly performed in acase where communication is performed on a C plane of GTP to form the L2tunnel. Further, rewriting is also applicable to a case where a tunnelsuch as an L3 tunnel is formed, other than the L2 tunnel.

In the above example of the present invention, the gateway 210 isisolated into the first group of servers 211, which is the partconnected with the MNO's communication infrastructure, and the secondgroup of servers 212, which is the part that performs additional dataprocessing and the like, whereby occupation of computing resources thatlimits the increase in the number of simultaneously connectable devicesof the gateway 210 is avoided even if the additional data processing inthe gateway 210 is added, and implementation of rich functions andcomplicated functions to the gateway 210 becomes possible.

Further, even if the additional data processing is not added, forexample, the first group of servers 211 substantially performs only therewriting of the IP address designated by the header of the receiveddata with one of the plurality of IP addresses to limit the dataprocessing in the first group of servers 211, so that the limitedcomputing resources in the first group of servers 211 are mainly usedfor forwarding to the second group of servers 212 that does not havesuch a limit and the number of simultaneously connectable devices can beimproved under the number limit of the gateways connectable with theMNO's communication infrastructure. As an example, tunneling processingof the GTP header may be performed in the second group of servers 212.

Further, for example, the main reason for the communication restrictionduring New Year's Holiday or in the new year is an excess in one ofdesign capacity of a CPU, a memory, a storage, and network traffic ofthe server that processes the communication. According to the presentembodiment, the IP address of the server with a low load is allocated onthe basis of metrics of the processing capability of the second group ofservers 212, or the processing is distributed by newly activating aserver when the capacity of the second group of servers 212 as a wholeis insufficient, whereby the number of simultaneously connectabledevices and the capacity of the communication system as a whole can beincreased.

In particular, each server constituting the second group of servers 212can be an instance on a cloud, and by doing so, the number of theinstances can be increased as needed to scale out, and the computingresources can be virtually inexhaustibly used.

In this specification, the term “cloud” refers to a system capable ofdynamically provisioning and providing computing resources such as aCPU, a memory, a storage, and a network bandwidth according to demand ona network. For example, the cloud can be used by AWS or the like.

Further, each server constituting the first group of servers 211 can bean instance on the cloud, and by doing so, the IP address of each servercan be virtualized to improve fault tolerance. The correspondencebetween the first group of servers 211 and the second group of servers212 can be held on a database of a third group of servers 500 describedbelow in a latest state in real time, for example. Even if a certainserver goes down, the fault can be instantaneously recovered byattaching the IP address to another server. In addition, scaling up andscaling down can be freely performed by using cloud. Therefore, aninstance having optimum CPU, memory, storage, and network bandwidth canbe selected according to a processing load. As a result, there is noneed to prepare hardware that meets the maximum demand at peak hour on aconstant basis, and cost optimization becomes possible. This alsoapplies to the utilization of cloud for the second group of servers 212.

An example of the IP network accessed by the wireless terminal, which isenabled by the present embodiment, includes a private system besides theInternet. In a case of realizing at least part of an on-premise privatesystem and the gateway 210 on cloud, a different IP network on the samecloud or an IP network on a different cloud are included in the privatesystem for example, and the communication system 200 or the gateway 210can be connected with the private system by a dedicated line or avirtual dedicated line.

(Control of Second Group of Servers)

In an embodiment of the present invention, as illustrated in FIG. 5, thecommunication system 200 further includes the third group of servers500, and controls the number of servers constituting the second group ofservers 212 on the basis of the metrics of the processing capability toscale in or scale out the second group of servers 212. The third groupof servers 500 monitors the metrics of the processing capacities of theinstances used in the first group of servers 211 and the second group ofservers 212, and can allocate connection to an instance with a lowprocessing load every time a connection request is given from thewireless terminal.

Examples of the metrics to be monitored include a CPU load, a memoryutilization rate, disk read, disk write, a network traffic receptionamount, and a network traffic transmission amount.

In addition, the correspondence between the first group of servers 211and the second group of servers 212 can be selected using the thirdgroup of servers 500. As illustrated in FIG. 6, when the first group ofservers 211 receives a GTP connection initiation request (GTP-C)including IMSI, TEID, and the like of the wireless terminal, the firstgroup of servers 211 transmits a CreateSession message to the thirdgroup of servers 500, and the third group of servers 500 that hasreceived the message can select the second group of servers 212 at thedestination on the basis of the metrics of the processing capacitycreated by continuously or intermittently monitoring use statuses of theCPU, the memory, the storage, the network traffic, and the like of thecomputing resources of the second group of servers 212. At the time ofthe GTP connection initiation request, correspondence among theidentifier of the L2 tunnel, the identification number of the wirelessterminal, the IP addresses of the first group of servers 211, and the IPaddresses of the second group of servers 212 is recorded in the thirdgroup of servers 500, whereby a session of the L2 tunnel can berecovered at the time of the fault of the first group of servers 211 orthe second group of servers 212.

In FIG. 6, the first group of servers 211 has received the connectioninitiation request and the first group of servers 211 serves thefunction on the C plane. However, a group of C plane servers that servesa function on the C plane can be separately provided as a part of thegateway 210 or a part of the communication system 200. In doing so, thecomputing resources of the first group of servers 211 can be used forsimultaneous connection with a larger number of devices. In this case,the first group of servers 211 does not receive the connectioninitiation request and has no function on the C plane.

Further, the third group of servers 500 can send a provisioning messageto a server with a less use status and a small performance metric at thetime of the GTP connection initiation in the second group of servers212, thereby to select the server with a small processing load from thesecond group of servers 212 and allocate a GTP connection destinationserver.

Then, as illustrated in FIG. 7, a server constituting the first group ofservers 211 forwards the data from the wireless terminal to one of thesecond group of servers 212 corresponding to the plurality of IPaddresses after rewriting. FIG. 7 illustrates that each of the firstgroup of servers 211 and the second group of servers 212 includes threeinstances, and the second group of servers 212 is shared by the serversof the first group of servers 211. However, an embodiment is not limitedto the example.

The number of the servers constituting the second group of servers 212favorably exceeds the number of the servers constituting the first groupof servers 211. If the number of the servers constituting the secondgroup of servers 212 is equal to or less than the number of the serversconstituting the first group of servers 211, resources such as thenumber of sessions, the number of IP flows, and the like, which aredetermined by the number of servers or instances, are not increased, andthus sufficient scalability may not be able to be exhibited.

When the processing load of the instance group as a whole of the secondgroup of servers 212 exceeds a set level, a new instance can beactivated and a server can be added. On the other hand, when theprocessing load of the instance group as a whole of the second group ofservers 212 falls below the set level, one of active instances isselected, and if there is an L2 tunnel or the like in communication, itcan be transferred to another instance, and then the selected instancecan be stopped. For example, the number of instances constituting thesecond group of servers 212 can be reduced to zero.

The third group of servers 500 can set the number of instances by whichthe second group of servers 212 is scaled in or scaled out, according toa predetermined schedule. For example, the number of instances isautomatically increased from 11:30 just before the lunch break time whencommunication demand comes to a peak, and the number of instances isautomatically decreased at 13:30 at off-peak time.

Note that, in the above example, the third group of servers 500 isprovided outside the gateway 210. However, the gateway 210 may includethe third group of servers 500, and the instances constituting thesecond group of servers 212 can constitute the third group of servers.

Further, the third group of servers 500 can include a common databaseand can perform processing in parallel in a plurality of instances.

(Additional Data Processing)

Specific examples of additional data processing available in the gateway210 by the present invention will be described.

Encryption

Data processing for payload encryption will be described with referenceto FIG. 8. The corresponding server of the second group of servers 212,which has received the payload to which the headers are added from thefirst group of servers 211, first removes all the headers. Then, afterencrypting a payload part of HTTP (HTTP payload), the server newly addsan HTTPS header and further reassigns the TCP/IP headers again.

With such data processing, encryption of the payload is performed onbehalf of the wireless terminal without applying a load to the firstgroup of servers 211 and so to say assumed by the server, and securityof communication can be enhanced. Especially, the communication system(communication platform) side can add required added value even awireless terminal such as an IoT device with relatively low performanceis used.

Note that, in the illustrated example, the payload part of TCP (TCPpayload) is encrypted. However, the payload part of IP (IP payload) canbe encrypted. In this case, the IP header included in the GTP payloadmay be removed once and the IP payload may be encrypted.

Credential Addition

The corresponding server in the second group of servers 212, which hasreceived the payload to which the headers are added from the first groupof servers 211, can identify the identifier included in the GTP headerin the process of removing the headers, thereby to specify subscriberinformation such as the identification number of the wireless terminalor the like. Therefore, for example, credentials such as a passwordaccompanying the subscriber information recorded in the database of thethird group of servers 500 can be obtained. The second group of servers212 can capture communication addressed to a specific HTTP server fromthe wireless terminal, generate a signature with credentials necessaryfor the HTTP server, and then transmit the data by HTTPS. The term“credentials” used here is a generic term for information used for userauthentication, including an ID and a password.

With such data processing, even the wireless terminal such as the IoTdevice that is powerless and has insufficient storage capacity canperform communication with a server on the Internet by adding thecredentials such as the password.

Proxy Storage

The first group of servers 211 receives data according to protocols suchas HTTP, MQTT, TELNET, FTP, and TCP transmitted from the wirelessterminal. The corresponding server of the second group of servers 212,which has received the payload to which the header is added from thefirst group of servers 211, first removes all the headers. Then, thecredentials necessary for storing data in a computing storage on a cloudor transfer data described by a data description language such as JSONis added, then the HTTP header is reassigned or the HTTPS header isnewly added after encrypting the HTTP payload part, and the data in thepayload can be stored in the computing storage or a database on thecloud.

With such data processing, even the wireless terminal such as the IoTdevice that is powerless and has insufficient storage capacity caneasily store data only by being provided with a communication function.

Protocol Conversion

A flow of data processing of protocol conversion will be described withreference to FIG. 9. An instance of the second group of servers 212,which has received, via the first group of servers 211, data transmittedfrom the wireless terminal toward the end point and carried by protocolssuch as HTTP, HTTPS, MQTT, TELNET, FTP, TCP, and the like, candiscriminate the subscriber information of the wireless terminal that isthe transmission source by identifying the identifier included in theGTP header when once removing all the headers. The transmission sourceIP address in the IP header is replaced such that the IP address of theinstance itself becomes a recipient of communication with an outside,and then information such as a password corresponding to the subscriberinformation is obtained from the database of the third group of servers500, for example, and the credentials such as an ID and the passwordincluded in the subscriber information of the wireless terminal areadded, then headers of other protocols (HTTP, HTTPS, MQTT, TELNET, FTP,TCP, IP, and the like) that are different from those when transmittedfrom the wireless terminal are reassigned, the payload part is encryptedor non-encrypted and can be transmitted to an arbitrary server (target)on the Internet.

With such additional data processing, even if the wireless terminal suchas an IoT device has a powerless processing capacity and a certainprotocol is difficult to have, the second group of servers 212 can servea relay function to conduct the protocol conversion to performcommunication under the protocol with a server on the Internet side.

Throughput Control

By measuring a data amount transmitted and received between the wirelessterminal and the IP network by the second group of servers 212, the datatraffic per unit time can be controlled. When a transmitted data amountfrom the wireless terminal or a received data amount exceeds a limitingvalue, the second group of servers 212 discards the IP packet or buffersthe IP packet for a fixed time, thereby to control a data flow rate. Asa result, throughput control becomes possible.

With such data processing, data can be transmitted to a large number ofIoT devices with a limited reception capacity by appropriate throughputcontrol without giving a load to the first group of servers 211.

Total Data Traffic Control

By measuring the data amount transmitted and received between thewireless terminal and the IP network by the second group of servers 212,transmitting the data amount to the third group of servers 500, andcontrolling transmission/reception traffic of individual wirelessterminal in the database of the third group of servers 500, the totaldata traffic can be controlled. Correspondence between the wirelessterminal and the second group of servers 212 can be determined asdescribed above when the GTP is connected, and thus the total datatraffic passing the second group of servers 212 cannot be measured byonly a specific server. However, by accumulating the data amount in realtime in the third group of servers 500, transmission or reception datacommunication from or to the wireless terminal can be stopped orthroughput can be controlled to have a flow rate of a fixed value orless when the data amount transmitted or received by the specificwireless terminal exceeds a set value within a fixed period.

With such data processing, the total data traffic of the individualwireless terminals can be accumulated in real time by the database ofthe third group of servers 500 without applying a load to the firstgroup of servers 211. Therefore, the total data traffic of a largenumber of wireless terminals such as IoT devices can be collectivelygrasped as one group.

Response and Priority Control

Processing of data to be transmitted from the Internet to a wirelessterminal can be performed with given priority. For example, datadestined for a SIM card with higher priority is placed in a transmissionqueue of a higher priority instance within transmission queues of thesecond group of servers 212, other data of a SIM card with low priorityis placed in a transmission queue of a low priority instance, andpriority transmission processing according to priority is performed byperforming processing first from the data in the transmission queue withhigher priority, whereby response performance can be controlled.Alternatively, by discarding the data to a SIM card with lower priorityby the second group of servers 212, data to a SIM card with higherpriority can be preferentially processed, and the response can beimproved.

With such data processing, an IoT device for which emergencynotification is required can be given higher priority, and can performdata communication with short response.

Time Zone Restriction

The corresponding server of the second group of servers 212, which hasreceived the payload to which the headers are added from the first groupof servers 211, determines data communication from a specific wirelessterminal and can stop the data communication depending on a time zone,or control the throughput to have a flow rate of a fixed value or less.For example, in a case of a wireless terminal permitted to communicateonly during a late night time period, a new request is not accepted bythe first group of servers 211 except the permitted time or thecommunication processing can be stopped by the second group of servers212 if a communication path has already been established.

With such data processing, data from an IoT device can be stopped whenthe wireless data communication comes to a peak, and conversely, thetime zone during which the wireless data communication is off-peak canbe effectively used.

Notifications and Program Execution

The first group of servers 211 receives data by a protocol such as HTTP,MQTT, TELNET, FTP, and TCP transmitted from a wireless terminal. Thecorresponding server of the second group of servers 212, which hasreceived the payload to which the headers are added from the first groupof servers 211, first removes all the headers. Then, an SMS or an e-mailis sent and notified to the destination on the basis of the informationstored in the third group of servers 500, or the payload is input to aprogram prepared in advance and a specific program is executed.

With such data processing, when a specific event such as a fault occurs,processing of notifying the event by e-mail or automatically executing adetermined program can be easily realized.

Resolution Conversion of Image/Video

To reduce a CPU processing load of a wireless terminal, resolution of animage or a video included in downlink data transmitted from the gateway210 to the wireless terminal can be changed. The second group of servers212 can determine the throughput by measuring the data transmissionamount per unit time for individual wireless terminal. When thethroughput falls below a fixed value or less, the second group ofservers 212 extracts image/video data included in transmission data andconverts the image/video data into a bit rate of codec conforming tocurrently available throughput and then can transmit the data to thewireless terminal.

With such data processing, the image or the video can be transmittedwithout transmission delay to an IoT device that requires real-timeproperties such as a surveillance camera.

Thin Client

While applications conforming to HTML 5 are increasing for mobileterminals such as smartphones and tablets, execution of suchapplications can be performed on the second group of servers 212, not onthe web browser of the mobile terminal, and only screen display can beperformed on the mobile terminal side.

To be specific, the gateway 210 side can serve, on behalf of the mobileterminal, a networking function (HTTP or HTTPS), an image or video datacompression function (optimize and reduce the data for a screen size ofthe mobile terminal), an image or video codec conversion function, a DRMaddition/conversion function, an interpreter (or compiler) function ofJavascript (registered trademark), a data caching function (with afunction to predict a page to be read next by a user), a renderingfunction (with the function to predict a page to be read next by auser), a data storage function, and the like.

The mobile terminal side may just serve a function as a display deviceas a limiting case, and necessary functions of an application can beperformed by the communication system (communication platform) side onbehalf of the mobile terminal.

(Public Cloud)

The communication system 200 can be implemented on a cloud, and inparticular can be implemented on a public cloud. Here, the “publiccloud” refers to a cloud usable by a plurality of tenants.

In the public cloud, computing resources are used by a plurality ofoperators in different patterns, as compared with a private cloud usedby a single operator. Therefore, a difference in utilization ratebetween at peak hour and at an average becomes small by statisticalmultiplexing effect. Therefore, the public cloud operators canefficiently operate large-scale computing resources. In the presentinvention, by sharing computing resources with operators other than thecommunication business on the public cloud, the computing resourcesnecessary at peak hour can be secured without limitation from the publiccloud.

REFERENCE SIGNS LIST

-   200 Communication system (communication platform)-   210 Gateway-   211 First group of servers-   212 Second group of servers-   500 Third group of servers

1. A communication system for providing an access to an IP network to awireless terminal, comprising a gateway for passing data from thewireless terminal to the IP network, wherein the gateway comprises afirst group of servers with a receiving unit for receiving data from thewireless terminal, a selecting unit for selecting one of a plurality ofdestination addresses based on a header of the received data, and aforwarding unit for forwarding the data to the destination addressselected by the selecting unit, wherein each of the first group ofservers forwards the data to a server constituting a second group ofservers corresponding to one of the plurality of destination addresses.2. The communication system according to claim 1, wherein the gateway isGGSN or P-GW.
 3. The communication system according to claim 1 or 2,further comprising: a group of C plane servers receiving a connectioninitiation request from the wireless terminal, wherein the processingperformed by the first group of servers is triggered by the connectioninitiation request received by the group of C plane servers.
 4. Thecommunication system according to claim 1, wherein the number of serversconstituting the first group of servers is equal to or less than apredetermined number.
 5. The communication system according to claim 4,wherein the predetermined number is determined by an MNO.
 6. Thecommunication system according to claim 1, wherein the number of serversconstituting the second group of servers exceeds the number of serversconstituting the first group of servers.
 7. The communication systemaccording to claim 1, each of the first group of servers and the secondgroup of servers has a correspondence table between a destinationaddress designated by the header and the plurality of destinationaddresses for each tunnel established by the wireless terminal.
 8. Thecommunication system according to claim 7, wherein the correspondencetable is associated with an identifier of a GTP header within theheader.
 9. The communication system according to claim 1, wherein theselecting unit specifies one of a plurality of destination addresses towhich the data is forwarded by rewriting a destination addressdesignated by the header.
 10. The communication system according toclaim 1, wherein the plurality of destination addresses is determined soas not to allocate the same address.
 11. The communication systemaccording to claim 1, wherein at least part of the plurality ofdestination addresses are the same.
 12. The communication systemaccording to claim 1, wherein an L2 tunnel is formed as a communicationchannel between the wireless terminal and the first group of servers.13. The communication system according to claim 1, wherein each serverconstituting the second group of servers is an instance on a cloud. 14.The communication system according to claim 13, wherein each serverconstituting the first group of servers is an instance on a cloud. 15.The communication system according to claim 14, wherein the second groupof servers is shared by servers of the first group of servers.
 16. Thecommunication system according to claim 13, comprising a third group ofservers connected to the second group of servers, wherein the thirdgroup of servers controls the number of servers constituting the secondgroup of servers.
 17. The communication system according to claim 16,wherein the third group of servers is constituted by instancesconstituting the second group of servers.
 18. The communication systemaccording to claim 13, wherein the number of instances constituting thesecond group of servers is reducible to zero depending on a processingload of the second group of servers.
 19. The communication systemaccording to claim 13, wherein the gateway is multi-tenant.
 20. Thecommunication system according to claim 1, wherein the second group ofservers performs data processing to the data.
 21. The communicationsystem according to claim 20, wherein the data processing is at leastone of encryption of payload of the data, protocol conversion of thedata, throughput control of data transmission from the wireless terminaland credential addition to payload of the data.
 22. The communicationsystem according to claim 1, wherein the second group of serversperforms downstream data processing to data transmitted from the gatewayto the wireless terminal.
 23. The communication system according toclaim 22, wherein the downstream data processing is at least one ofresolution conversion of an image or a video included in the data,throughput control of data reception by the wireless terminal, prioritycontrol of data reception by the wireless terminal and execution of afunction compliant with HTML5.
 24. A communication method for providingan access to an IP network to a wireless terminal, comprising steps of:a first group of servers of a gateway for passing data from the wirelessterminal to the IP network receiving data from the wireless terminal atthe gateway; the first group of servers selecting one of a plurality ofdestination addresses based on a header of the received data; and thefirst group of servers forwarding the data to the selected destinationaddress, wherein each of the first group of servers forwards the data toa server constituting a second group of servers corresponding to one ofthe plurality of destination addresses.
 25. A program for having agateway for passing data from a wireless terminal to an IP network toperform a communication method for providing an access to the IP networkto the wireless terminal, the communication method comprising steps of:a first group of servers of the gateway receiving data from the wirelessterminal at the gateway; the first group of servers selecting one of aplurality of destination addresses based on a header of the receiveddata; and the first group of servers forwarding the data to the selecteddestination address, wherein each of the first group of servers forwardsthe data to a server constituting a second group of serverscorresponding to one of the plurality of destination addresses.